A regular polyhedron is defined as a polyhedron all of whose faces are regular congruent polygons and all of whose vertices have the same number of edges (ridges) meeting together at each thereof. According to the Euler's polyhedron theorem, such a regular polyhedron can exist only in the following five types: a regular tetrahedron, a regular hexahedron, a regular octahedron, a regular dodecahedron, and a regular icosahedron. For example, to form a regular dodecahedron 01, as shown in FIGS. 39 and 40, of a raw metal material, the raw material shaped into a cube can be milled twelve times at a vertex angle of 108 degrees using a computer-controlled milling machine, or can also be shaped using a polyhedron shaping machine disclosed in Japanese Patent Laid-Open Publication No. Hei 9-285923. Alternatively, the regular dodecahedron 01 can also be shaped by casting molten metal into a casting die.
For a raw material of metal, the aforementioned shaping methods would make it possible to readily obtain a regular dodecahedron. However, for a raw material of stone, the milling cutter cannot be used for grinding the stone workpiece to be milled. With the shaping machine according to Japanese Patent Laid-Open Publication No. Hei 9-285923 mentioned above, it is almost impossible to chuck and shape with high accuracy a polyhedron having a complicated structure such as a regular dodecahedron or a regular icosahedron. Furthermore, a material of stone is not compatible with die casting. As such, it was difficult to manufacture ornaments, such as a memorial stone, an object, or a tomb stone, which are formed of a raw material of stone in the shape of a regular dodecahedron or a regular icosahedron. In this context, the applicant has devised the present invention in view of this problem. It is therefore an object (theme) of the invention to provide a method for easily manufacturing a regular polyhedron such as a regular dodecahedron or a regular icosahedron. It is another object of the invention to provide an ornament manufactured according to the method. In the method, a stone is pre-shaped into a cube in preparation for a raw workpiece, and on this cubic workpiece, cutting base lines are drawn which define faces and ridges obtained from the geometric features of a regular dodecahedron or a regular icosahedron. Auxiliary lines are drawn every time each face of the regular polyhedron is ground based on the cutting base lines, and then a next new face is cut based on the auxiliary lines and the cutting base lines. The regular polyhedron is thus manufactured, and an ornament manufactured according to the method is provided.